Aa. Madej et al., RB ATOMIC-ABSORPTION LINE REFERENCE FOR SINGLE SR+ LASER COOLING SYSTEMS, Applied physics. B, Lasers and optics, 67(2), 1998, pp. 229-234
The near coincidence of the Rb-85, 5s S-2(1/2)(F '' = 2) --> 6p P-2(1/
2) (F' = 2, 3) absorption resonance with the Sr-88(+), 5s S-2(1/2) -->
5p P-2(1/2) transition is exploited to provide a simple, effective fr
equency reference for a laser cooling/fluorescence excitation source a
pplied to single Sr+ ions. A modulation-free frequency stabilization s
ystem has been designed which uses the differential signal from two fr
equency-displaced beams traversing a Rb cell and which probe the Doppl
er-broadened Rb S-P lineshape at microwatt power levels. The method is
applied to frequency lock a 422-nm frequency-doubled diode laser syst
em that is used for excitation of a single Sr-88(+) ion. Stable, long-
term laser cooling and fluorescence are achieved using the frequency-s
tabilized 422-nm source resulting in observed ion confinement times wi
thout adjustment of over 8 h, together with an improvement in single-i
on loading efficiency.